To improve treatment for patients with large akinetic or dyskinetic regions in the left ventricular myocardium, excision of the defect and implantation of a mechanical functional equivalent of myocardium is proposed. Our prior investigations utilizing a working prototype of the prosthetic myocardium suitable for short-term hemodynamic studies indicated substantial hemodynamic benefits in dogs with induced failure but did not establish whether the increment in myocardial performance resulted from the prosthesis or from increased myocardial work. To test the hypothesis that the improvements result from the physiologic effects of prosthesis activation, and to quantitate these effects, left ventricular function curves will be constructed according to classical experimental protocols, with documentation of concomitant myocardial oxygen utilization. Should these investigations confirm the physiologic efficacy of the approach, further investigations will be desirable to elucidate its potential as a distinctively specific form of therapy for large ventricular infarcts and their sequelae.